All of the following are color units of measurement EXCEPT?

In the context of hair coloring and cosmetology, color units of measurement typically help professionals understand and categorize the various aspects of hair color.

Levels refer to the lightness or darkness of a color on a scale, commonly from 1 (darkest) to 10 (lightest). They allow colorists to identify how light or dark a hair color is.

Warmth describes the quality of a color in terms of its heat or coolness, such as whether it has golden, copper, or ash tones.

Undertones refer to the subtle hues that exist beneath the primary color of the hair. For example, even if a color appears blonde, it might have underlying warmth from a golden or yellow tone or coolness from an ash tone.

Dominant, however, does not refer to a standard measurement unit but rather describes a primary influencing characteristic of color. It typically signifies which color is most prominent in a mixture or composition but does not serve as a unit of measurement itself in the context of hair coloring. Therefore, it stands apart from the other options, making it the exception among units of measurement in color.